Hearing loss may be more common among individuals with a developmental disability than in the general population, and it carries additional complications in this patient group that the average audiologist does not typically face. Hearing aids are usually used to improve communication skills, but an innovative application can help control unwanted behaviors in those with multiple handicaps and developmental disabilities.
The incidence of hearing loss within an institutional population reportedly varies from eight percent to 56 percent depending on the test protocol and the criteria used to define it.1 Actual incidence rates are difficult to come by because of the unreliability of subjective responses, the lack of objective measurement tools at most facilities, and the need for sedation to complete electrophysiological measures, such as auditory evoked potentials. But the incidence among the noninstitutionalized developmentally disabled has been reported to be three times that for the population at large.1
The Corpus Christi State Supported Living Center in Texas serves approximately 260 adult residents with developmental disability and a wide range of function, needing anywhere from complete care for daily living to a little support. The primary concern in this population is maintaining good health while helping each individual reach his potential. This population presents unique challenges to the audiologist because only a small proportion of the residents are capable of responding to conventional audiometric tests, and few are willing or able to sit through an extended subjective diagnostic exam.
Auditory evoked potentials, such as the auditory steady-state response, may provide useful information, but the equipment for this test is not available in our facility and would require sedation in most cases. The risks and cost of routine sedation cannot be justified unless it contributes to better patient care. Otoacoustic emissions are used routinely in our facility to provide objective information regarding outer hair cell function, but they do not provide information about higher neurological function, specifically hearing. A certain amount of patient cooperation is required for emissions testing, and some of our residents can barely tolerate a quick tympanogram. Some will not even allow otoscopy.
Additional challenges exist to develop and implement rehabilitative hearing care for those with hearing loss, ranging from the management of chronic outer and middle ear infections to daily maintenance of hearing aids, which is a lower priority because of the number of unpredictable events that can happen. Remembering to change the battery on someone's hearing aid may not be a top concern when a number of individuals are going in opposite directions at the same time.
This population has different concerns from the general population, such as a higher incidence of cerumen production. Our residents require cerumen removal every two months to avoid impaction. Removing cerumen may cause extra distress because of residents’ lack of comprehension, the need to place objects in the ear canal, and a general resistance to clearing the cerumen. From a practical standpoint, the audiologist may need to keep one eye on the patient to avoid being assaulted while the other eye is on the otoscope during cerumen removal. More than one-third of our population is seen for cerumen management while sedated for another procedure such as dental care. This has been a successful system done in cooperation with the dental department and anesthesiologists.
Each resident is a unique individual and deserves respect for his choices. Dormitory living can present challenges given the diversity of personalities and needs, however. Anyone who has ever lived in a college dormitory understands that one must accommodate individual differences and tolerate various behaviors.
A Unique Application
A 57-year-old woman had been institutionalized at our facility since she was 21. She has a Cattell mental age of 9 months and an IQ below 20. Her personal and social skills are rated at 9 months, motor skills at 5 months, and language skills at 8 months. She has limited mobility and is confined to a wheelchair. She has a history of chronic ceruminosis with normal middle ear function via tympanometry, and she does not respond to conventional audiometric testing. Conditioning audiometry was unsuccessful. Sound-field speech detection thresholds throughout the years ranged from 25 to 55 dB HL. She was startled by loud sounds at 75 dB HL and during one test reportedly covered her ears at 70 dB HL. Her hearing, for all functional purposes, appeared adequate for her limited communication needs.
The patient frequently screamed for prolonged periods of time, which limited audiometric testing. Her occupational therapist asked if there was a way to help with this behavior. A trial with a personal amplifier was implemented to assess if amplified sound would present a negative reinforcer to reduce her screaming. The personal amplifier was set to one-half volume, which presented approximately 30 dB of gain, maximum power output of 133 dB SPL, and a bandwidth of 275 to 9,000 Hz without bass reduction. She screamed during the initial fitting, and no overt response was observed from the amplified screaming. She was scheduled for weekly appointments to monitor her progress and verify the amplifier's operation.
Her attendant reported no overt responses to sound and no change in her screaming at the first follow-up but reported that the patient removed the earphones on occasion. The patient was not seen by an audiologist for two months because of various circumstances, including a prolonged stay in the infirmary, but when she returned, she was using the device, and her attendant reported that the frequency of her screaming had diminished. An ear impression was taken to begin a trial with a BTE hearing aid. Her left ear was fit with a hearing aid with a three-quarter shell Lucite earmold and a select-a-vent. The left ear was selected because she frequently lies on her right ear when seated in her wheelchair. An audiogram was not available, so the audiogram shown in the Figure was used to program the hearing aid. The Table shows the programming values, which included a maximum power output of 112 dB SPL at 2,000 Hz, a relatively low knee point, a compression ratio of one, and gain values for conversational speech (65 dB input) from 26 to 40 dB. No particular special features of the hearing aid were turned on, the volume control was disabled, and only one memory was used.
The patient showed no observable response to her name at the fitting, so the average gain was increased 3 dB, but there was no detected response at this level either. She was wearing the hearing aid at the one-week follow-up, but the earmold had caused slight irritation to the inferior concha and was adjusted to reduce irritation.
The staff verified that the patient screams infrequently having worn the hearing aid for several months, and the dorm nurse said she now prefers quiet areas, spends her time gazing out the window, is able to participate in off-campus outings, and seems to enjoy sensory activities such as listening to music. She also appears to be much calmer and serene when she sees her audiologist.
Hearing is an important sense that helps people interact better with their environment, and it is well known that hearing is a distance sense that interacts synergistically with all of the other senses. The patient's hearing appeared functionally adequate for her communication needs, but amplification facilitated a sense of calm, which reduced her screaming and made life more pleasant for her, the staff, and fellow dormitory residents.
It is not known if amplification was simply a negative reinforcer or if the presence of amplification improved her interaction with her environment. Studies with hearing-impaired seniors have reported that those with untreated hearing loss have less social activity and a higher incidence of depression, anxiety, paranoia, emotional turmoil, and insecurity. Seniors who use hearing aids felt better about themselves and saw improvements in their mental health, independence, security, and family relationships. (National Council on Aging, 1999; see FastLinks). Perhaps hearing aids may do the same for individuals with developmental disability.
* Read the National Council on Aging's report at http://bit.ly/NatCouncilAging.
* Click and Connect! Access the links in The Hearing Journal by reading this issue on our website or in our new iPad app, both available at thehearingjournal.com.
* Comments about this article? Write to HJ at HJ@wolterskluwer.com.